Support 3f swipe for tab scrubbing

chrome/browser/ui/views/ash/tab_scrubber.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/views/ash/tab_scrubber.h"
 
 #include "ash/shell.h"
 #include "ash/wm/window_util.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/browser/ui/views/frame/browser_view.h"
 #include "chrome/browser/ui/views/tabs/tab.h"
 #include "chrome/browser/ui/views/tabs/tab_strip.h"
 #include "chrome/common/chrome_notification_types.h"
 #include "content/public/browser/notification_source.h"
 #include "ui/aura/window.h"
 #include "ui/base/events/event.h"
+#include "ui/base/events/event_utils.h"
+
+namespace {
+Tab* GetTabAt(TabStrip* tab_strip, gfx::Point point) {
+  for (int i = 0; i < tab_strip->tab_count(); ++i) {
+    Tab* tab = tab_strip->tab_at(i);
+    if (tab_strip->tab_at(i)->bounds().Contains(point))
+      return tab;
+  }
+  return NULL;
+}
+
+const int kInitialTabOffset = 10;

[sky, 2012/11/28 23:36:19]

nit: constants before methods, and add a description.

+}
 
 // static
 TabScrubber* TabScrubber::GetInstance() {
   static TabScrubber* instance = NULL;
   if (!instance)
     instance = new TabScrubber();
   return instance;
 }
 
 TabScrubber::TabScrubber()
     : scrubbing_(false),
       browser_(NULL),
-      initial_tab_index_(-1),
-      initial_x_(-1) {
+      scroll_x_(-1),
+      scroll_y_(-1) {
   ash::Shell::GetInstance()->AddPreTargetHandler(this);
 }
 
 TabScrubber::~TabScrubber() {
 }
 
-ui::EventResult TabScrubber::OnMouseEvent(ui::MouseEvent* event) {
-  Browser* browser = GetActiveBrowser();
-
-  if (!(event->type() == ui::ET_MOUSE_PRESSED ||
-      event->type() == ui::ET_MOUSE_DRAGGED ||
-      event->type() == ui::ET_MOUSE_RELEASED))
-    return ui::ER_UNHANDLED;
-
-  if (!browser ||
-      (event->type() == ui::ET_MOUSE_RELEASED) ||
-      !(event->flags() & ui::EF_CONTROL_DOWN) ||
-      !(event->flags() & ui::EF_LEFT_MOUSE_BUTTON) ||
-      (browser_ && browser != browser_)) {
+ui::EventResult TabScrubber::OnScrollEvent(ui::ScrollEvent* event) {
+  if (event->type() == ui::ET_SCROLL_FLING_CANCEL) {
     if (scrubbing_)
       StopScrubbing();
     return ui::ER_UNHANDLED;
   }
 
+  if (event->finger_count() != 3 ||
+      event->type() != ui::ET_SCROLL)
+    return ui::ER_UNHANDLED;
+
+  Browser* browser = GetActiveBrowser();
+  if (!browser || (browser_ && browser != browser_)) {
+    if (scrubbing_)
+      StopScrubbing();
+    return ui::ER_UNHANDLED;
+  }
+
+  BrowserView* browser_view =
+      BrowserView::GetBrowserViewForNativeWindow(

[sky, 2012/11/28 23:36:19]

BrowserView::GetBrowserViewForBrowser(browser);

+          browser->window()->GetNativeWindow());
+  TabStrip* tab_strip = browser_view->tabstrip();
+
+  float x_offset = -event->x_offset();
   if (!scrubbing_) {
     scrubbing_ = true;
-    initial_x_ = event->x();
     browser_ = browser;
-    initial_tab_index_ = browser_->active_index();
+    Tab* initial_tab = tab_strip->tab_at(browser_->active_index());
+    scroll_x_ = initial_tab->x();
+    scroll_x_ += (x_offset < 0) ?
+        kInitialTabOffset : initial_tab->width() - kInitialTabOffset;
+    scroll_y_ = initial_tab->height() / 2;
     registrar_.Add(
         this,
         chrome::NOTIFICATION_BROWSER_CLOSING,
         content::Source<Browser>(browser_));
-  } else {
-    BrowserView* browser_view =
-        BrowserView::GetBrowserViewForNativeWindow(
-            browser_->window()->GetNativeWindow());
-    TabStrip* tab_strip = browser_view->tabstrip();
-    Tab* initial_tab = tab_strip->tab_at(initial_tab_index_);
-    if (!initial_tab) {
-      StopScrubbing();
-      return ui::ER_UNHANDLED;
-    }
+  }
 
-    gfx::Point tab_point((initial_tab->width() / 2) + event->x() - initial_x_,
-                         initial_tab->height() / 2);
-    Tab* new_tab = tab_strip->GetTabAt(initial_tab, tab_point);
-    if (new_tab && !new_tab->IsActive()) {
-      int new_index = tab_strip->GetModelIndexOfTab(new_tab);
-      browser->tab_strip_model()->ActivateTabAt(new_index, true);
-    }
+  if (ui::IsNaturalScrollEnabled())
+    scroll_x_ += event->x_offset();
+  else
+    scroll_x_ -= event->x_offset();
+  Tab* first_tab = tab_strip->tab_at(0);
+  Tab* last_tab = tab_strip->tab_at(tab_strip->tab_count() - 1);
+  if (scroll_x_ < first_tab->x())
+    scroll_x_ = first_tab->x();
+  if (scroll_x_ > last_tab->bounds().right())
+    scroll_x_ = last_tab->bounds().right();
+
+  gfx::Point tab_point(scroll_x_, scroll_y_);
+  Tab* new_tab = GetTabAt(tab_strip, tab_point);
+  if (new_tab && !new_tab->IsActive()) {
+    int new_index = tab_strip->GetModelIndexOfTab(new_tab);
+    browser->tab_strip_model()->ActivateTabAt(new_index, true);
   }
 
   return ui::ER_CONSUMED;
 }
 
 void TabScrubber::Observe(int type,
                           const content::NotificationSource& source,
                           const content::NotificationDetails& details) {
   DCHECK(type == chrome::NOTIFICATION_BROWSER_CLOSING &&
          content::Source<Browser>(source).ptr() == browser_);
   StopScrubbing();
 }
 
 Browser* TabScrubber::GetActiveBrowser() {
   aura::Window* active_window = ash::wm::GetActiveWindow();
   if (!active_window)
     return NULL;
 
   Browser* browser = browser::FindBrowserWithWindow(active_window);
   if (!browser || browser->type() != Browser::TYPE_TABBED)
     return NULL;
 
   return browser;
 }
 
 void TabScrubber::StopScrubbing() {
+  if (!scrubbing_)
+    return;
+
   registrar_.Remove(
       this,
       chrome::NOTIFICATION_BROWSER_CLOSING,
       content::Source<Browser>(browser_));
   scrubbing_ = false;
   browser_ = NULL;
-  initial_tab_index_ = -1;
 }